get default hr and power zones from config file

CLAUDE.md

@@ -67,7 +67,7 @@ site/                      Astro project
       ActivityFeed.svelte   Card grid, sport filter, pagination
       ActivityDetail.svelte Map + stats + charts wrapper
       ActivityMap.svelte    MapLibre GL (gradient track, linked hover dot)
-      ActivityCharts.svelte Observable Plot (elevation/speed/HR/cadence tabs)
+      ActivityCharts.svelte Observable Plot (elevation/speed/HR/cadence/power tabs)
       StatsView.svelte      Yearly heatmap + totals
     lib/
       types.ts              BAS TypeScript types
@@ -199,6 +199,46 @@ const intensity = 0.12 + pctRank(total, sortedDaily) * 0.88;
   detects the dependency change when the sport filter or scale method changes
   (plain function calls with static args don't trigger Svelte re-renders).
 
+## ActivityCharts — controls and athlete zones
+
+`ActivityCharts.svelte` renders Observable Plot charts for the activity detail page.
+
+### Chart controls
+
+- **Metric tabs**: Elevation · Speed · Heart Rate · Cadence · Power
+- **Chart type toggle** (right-aligned): `↗ Line` | `▭ Hist`
+- **X-axis toggle** (line mode only, shown when speed data present): `Time` | `Dist`
+  - Distance is integrated from `speed_kmh` at 1 Hz — no extra data needed.
+- **Histogram controls** (visible only in histogram mode):
+  - **Dual range slider** — trims the x domain; two overlapping `<input type="range">` with CSS track highlight.
+  - **Bins slider** — exact bin count using explicit evenly-spaced thresholds (not d3's "nice" count, which ignores narrow ranges).
+
+### Athlete zones
+
+Zones are configured in `extract_config.yaml` under `athlete:` and written into
+`index.json` at extract time (`owner.athlete`). The Astro activity page reads them
+from the index and passes them down: `[id].astro` → `ActivityDetail` → `ActivityCharts`.
+
+When viewing HR or Power in histogram mode, zone boundaries are drawn as dashed
+vertical rules with Z1–Z5/Z7 labels at the top of the chart.
+Labels and rules are clipped to the current trim range automatically.
+
+Zone color palettes:
+- HR (5 zones):    `#60a5fa #4ade80 #facc15 #fb923c #f87171`
+- Power (7 zones): `#60a5fa #34d399 #facc15 #fb923c #f87171 #c084fc #f43f5e`
+
+### Zone calculation reference (Coggan)
+
+| Zone | HR (% max HR) | Power (% FTP) |
+|------|--------------|---------------|
+| Z1 | < 55% | < 55% |
+| Z2 | 55–75% | 55–75% |
+| Z3 | 75–87% | 75–90% |
+| Z4 | 87–93% | 90–105% |
+| Z5 | > 93% | 105–120% |
+| Z6 | — | 120–150% |
+| Z7 | — | > 150% |
+
 ## Activity sidecar edits — design spec
 
 Users edit activities via **sidecar markdown files** that live alongside BAS JSON in the data dir.
@@ -348,6 +388,13 @@ are served at `data/activities/images/{id}/{filename}` by the Astro dev server.
 - [x] `PUBLIC_EDIT_URL` feature flag — unset = no edit UI, set = drawer enabled
 - [x] Markdown rendering in activity description with image path rewriting
 - [x] `hide_stats` support in activity detail stats panel
+- [x] ActivityCharts power tab (elevation/speed/HR/cadence/power)
+- [x] Chart type toggle: line ↔ histogram
+- [x] X-axis toggle: time ↔ distance (integrated from speed)
+- [x] Histogram dual range slider + bins slider (exact thresholds)
+- [x] Athlete zones in `extract_config.yaml` → `index.json` → chart overlays
+- [x] StatsView heatmap click-to-pin tooltip (Esc / click-outside to dismiss)
 - [ ] `bincio render --watch` incremental rebuild on sidecar/data changes
 - [ ] Highlight badge in activity feed cards
 - [ ] Image format warning (HEIC → JPEG conversion hint in the upload UI)
+- [ ] HR / power zone defaults from `max_hr` / `ftp_w` when explicit zones not set